Volume 13, Issue 1 (January 1985)
A Method for the Defined Fatigue Precracking of Round Notched Bars
This paper is concerned with the method of crack length controlled prefatiguing of notched round tension specimens. Since a direct optical analysis of the crack length in the present specimen is not possible, the change in the specimen stiffness is used to determine the crack depth. For this purpose, the deflection of the specimen is measured by laser technique during prefatiguing under reversed bending stressing. Comparing the measurement data with parameters determined by calculation from the transfer matrix method enables the crack depth to be determined on-line at any time of the prefatiguing process.